Django, ошибка InlineModelAdmin.get_extra, в чем проблема?

Question

[Mooris]

Здравствуйте, проблема вот в чем, необходимо было возвратить количество дополнительных встроенных форм, взял с документации этот код

InlineModelAdmin.get_extra

class BinaryTreeAdmin(admin.TabularInline):
    model = BinaryTree

    def get_extra(self, request, obj=None, **kwargs):
        extra = 2
        if obj:
            return extra - obj.binarytree_set.count()
        return extra

возвращает все отлично, но при добавлении и сохранении выдает ошибку
django.core.exceptions.ValidationError: ["Значение '' должно быть целым числом."]
моя модель такая

class Jurnal(models.Model):
    pos = models.AutoField(unique=True, primary_key=True)
    client = models.ForeignKey(Client, on_delete=models.CASCADE, db_column='client_id',)
    data = models.DateField(default=date.today, blank=True, null=True)
    time = models.TimeField(default=datetime.datetime.now, blank=True)

admin.py

class JurnalInline(admin.TabularInline):
    model = Jurnal
    def get_extra(self, request, obj=None, **kwargs):
        extra = 5
        if obj:
            return extra - obj.jurnal_set.count()
        return extra

Comments

[javedimka]

Есть полная ошибка?

[Mooris]

javedimka:

spoiler

Traceback (most recent call last):
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\db\models\fields\__init__.py", line 938, in to_python
    return int(value)
ValueError: invalid literal for int() with base 10: ''

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\core\handlers\exception.py", line 41, in inner
    response = get_response(request)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\core\handlers\base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\core\handlers\base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\contrib\admin\options.py", line 551, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\utils\decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\views\decorators\cache.py", line 57, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\contrib\admin\sites.py", line 224, in inner
    return view(request, *args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\contrib\admin\options.py", line 1511, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\utils\decorators.py", line 67, in _wrapper
    return bound_func(*args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\utils\decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\utils\decorators.py", line 63, in bound_func
    return func.__get__(self, type(self))(*args2, **kwargs2)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\contrib\admin\options.py", line 1408, in changeform_view
    return self._changeform_view(request, object_id, form_url, extra_context)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\contrib\admin\options.py", line 1447, in _changeform_view
    if all_valid(formsets) and form_validated:
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 460, in all_valid
    if not formset.is_valid():
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 321, in is_valid
    self.errors
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 295, in errors
    self.full_clean()
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 344, in full_clean
    form = self.forms[i]
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\utils\functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 144, in forms
    for i in range(self.total_form_count())]
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\formsets.py", line 144, in <listcomp>
    for i in range(self.total_form_count())]
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\models.py", line 895, in _construct_form
    form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\forms\models.py", line 594, in _construct_form
    pk = to_python(pk)
  File "C:\Users\admin\AppData\Roaming\Python\Python36\site-packages\django\db\models\fields\__init__.py", line 943, in to_python
    params={'value': value},
django.core.exceptions.ValidationError: ["Значение '' должно быть целым числом."]
[19/May/2017 15:36:44] "POST /admin/clients/client/10007/change/ HTTP/1.1" 500 160192

[javedimka]

Mooris: Изменяешь существующий объект или создаешь новый?

[Mooris]

javedimka: создаётся новый объект

[javedimka]

Mooris: попробуй сначала сохранить клиента без журналов, а потом уже через редактирование добавлять журналы